Control valve block for hydraulically operated elevators

ABSTRACT

A control valve block assembly for hydraulically operated elevators or the like comprising a single pressure differential balance means for both directions of travel of the elevator, this pressure differential balance means incorporating a control piston. Means define an intermediate channel communicating with the cylinder of the elevator drive unit, with said control piston maintaining in said intermediate channel the pressure deviating from the load pressure in the elevator cylinder by a constant amount. Reversing piston means serve to determine the deviation of the pressure at the high side or the low side of such load pressure, depending upon the direction of travel of the elevator. Further, dosing piston means is provided which in its open position provides a flow communication from said pressure differential balance means to said cylinder and thus regulates the quantity of hydraulic fluid medium flowing to and from such cylinder. Two electromagnets are also provided, each of which is operatively coupled with one precontrol slide means, and when energized actuates its associated precontrol slide means, one such precontrol slide means directly controlling the position of said control piston and the other precontrol slide means directly controlling the position of said dosing piston means.

United States Patent Haussler 3,687,011 Aug. 29, 1972 [72] Inventor: Hubert Haussler, Zug, Switzerland [73] Assignee: Beringer-Hydraulik R; Beriuger 8:

Co., Neuheim/Zug, Switzerland 22 Filedz April 21, 1970 [21] Appl. No.: 30,378

[30] Foreign Application Priority Data April 25, 1969 Switzerland ..6338/69 52 U.S.Cl "91/459 51 Int. Cl ..Fl5b 13/044 [58] FieldofSearch ..91/459, 275, 361,461,304; 187/17 [56] References Cited UNITED STATES PATENTS 2,737,197 3/1956 Jaseph ..187/17 3,120,880 2/1964 Jaseph ..91/461x 3,438,398 4/1969 Johnston ..91/461X 3,508,468 4/1970 Walter ..'...91/461X FOREIGN PATENTS OR APPLICATIONS 1,268,801 5/1968 Germany ..187/17 1,431,063 11/1968 Germany ..187/17 Primary Examiner-Martin P. Schwadron Assistant Examiner-Irwin C. Cohen Attorney-Werner W. Kleeman [57] ABSTRACT A control valve block assembly for hydraulically operated elevators or the like comprising a single pressure differential balance means for both directions of travel of the elevator, this pressure differential balance means incorporating a control piston. Means define an intermediate channel communicating with the cylinder of the elevator drive unit, with said control piston maintaining in said intermediate channel the pressure deviating from the load pressure in the elevator cylinder by a constant amount. Reversing piston means serve to determine the deviationof the pressure at the high side or the low side of such load pressure, depending upon the direction of travel of the elevator. Further, dosing piston means is provided which in its open position provides a flow communication from said pressure differential balance means to said cylinder and thus regulates the quantity of hydraulic fluid medium flowing to and from such cylinder. Two electromagnets are also'provided, eachof which is operatively coupled with one precontrol slide means, and when energized actuates its associated precontrol slide means, one such precontrol slide means directly controlling the position of said control piston and the other precontrol slide means directly controlling the position of said dosing piston means,

18Claims,2DrawingFigures Patented Aug. 29, 1972 3,687,011

2 Sheets-Sheet l INVENT OR v l/GGEk 7' K406516151? ATTORNEY Patented Aug. 29, 1972 2 Sheets-Sheet 2 I'll llllllll Raise Ve Ioify Leo: 55 t'll Cur/en! Applied Without Cum/1f Y-Sfart of Motor INVENTOR 64/82 Muss; ale

ATTORNEY CONTROL VALVE BLOCK FOR HYDRAULICALLY OPERATED ELEVATORS BACKGROUND OF THE INVENTION The present invention relates to a new and improved control valve block assembly for hydraulically actuated elevators or lifts.

In the last fewyears the proportion of I hydraulically operated elevators or lifts, in relation to the total number of lifts built, has continuously increased. While previously primarily slow moving freight elevators were equipped with hydraulic drives, nowadays rapidly travelling personnel lifts or elevators are also driven hydraulically. Quite obviously, the requirements which are placed upon hydraulic controls increase with travelling speed, so that for rapidly moving elevators or lifts there can be only employed control valve blocks which have been especially constructed for this purpose. The requirements which are placed upon such type control valve blocks can be individually enumerated a follows:

1. Load-independent travelling speeds in both directions.

2. Load-independent infinite acceleration and deceleration in both directions.

3. Load-independent crawling speed and short switching times for stopping exactly at a desired level.

4. Sealing of the cylinder conduits so as to be free of leakage oil in order to maintain the position of the elevator or lift after it has remained stationary for a long period of time.

5. Pressureless circulation when the valve is not supplied with current for the unloaded star-delta starter of the pump motor.

6. Electrical control with as few as possible actuation magnets having lower current consumption.

These requirements have not been satisfactorily fulfilled by the previously known prior art controls, or, at the very best, then only fulfilled for low travelling speeds. Most of the controls are dependent upon load, that is to say, the travelling speed is a function of the load. This is not desirable since it impairs the accuracy in stopping of the elevator. With numerous lifts or elevators of simpler construction, for instance of the type used as freight elevators, one of necessity had to be content with over-shooting or travelling past the selected story or floor of the building when the elevator was raised and thereafter to slowly permit the elevator cabin to drop to the desired level of the floor, whereas when the elevator cabin was travelling down it was necessary to decelerate such cabin long prior to reaching the desired floor level. In each instance, this results in an unnecessary time loss. If such should be prevented, and if there should be achieved a load-independent control, then further additional devices are required which increase the overall cost of the installation. Thus, for instance, in a control which has become known to the art up to eight control valves are required, which necessitate a great deal of space.

Furthermore, control blocks or units have become known in which for the upward and downward travel a respective separate control valve is required. This solution is equally expensive and requires a great deal of space.

Furthermore, it is of importance for a hydraulically operated elevator or lift that the cabin, even when the elevator is standing still for a longer period of time, does not slowly drop out of its position. Therefore, it has been intended to prevent this dropping or lowering of the elevator, brought about by leakage oil losses, by providing a special construction for one of the work pistons.

SUMMARY OF THE INVENTION Accordingly, it is a primary objective of the present invention to provide a new and improved control valve block or unit which effectively prevents the aforementioned drawbacks of the prior art constructions.

Another, more specific'object of the present invention relates to an improved hydraulic control system for elevators or lifts which is relatively simple in construction, extremely reliable in operation, provides for accurate control of the elevator-throughout various speed modes, and effectively over comes the aforementioned disadvantages associated with the prior art constructions, while fulfilling the requirements placed upon devices of this type as heretofore enumerated.

Now, in order to implement these and still further objects of the invention, which will become more readily-apparent as the description proceeds, the inventive control valve block or unit for hydraulically operated elevators or lifts is generally manifested by the features that there is provided only a single pressure differential balance for both directions of travel, the control piston of which maintains the pressure in an intermediate channel communicating with the cylinder of the elevator drive unit, which pressure deviates by a constant amount from the load pressure in such cylinder. This deviation towards the high side or the low side, depending upon the direction of travel of the elevator, being determined by a switching or reversing piston. Furthermore, the invention contemplates the provision of a dosing piston member constructed as a sealing seat valve which in open position provides a communication of the pressure differential balance to the cylinder, and thus quantitatively controls the hydraulic fluid flowing to and from, respectively, this cylinder. Additionally,

the invention contemplates the provision of two electromagnets which in their energized state actuate a respective precontrol slide, wherein one such precontrol slide directly controls the position of the control or regulating piston and the other precontrol slide directly controls the position of the dosing piston member.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description make reference to the annexed drawings wherein:

FIG. 1 is a schematic, partially sectional view, of a preferred embodiment of inventive control valve block or unit, and

FIG. 2 is a known motion or travel graph for an elevator in which, however, there has additionally been added the momentary operational duration of the hydraulic pump and the control magnets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS GENERAL DESCRIPTION:

. Describing generally now the drawings, it will be understood that for clarity in understanding there will initially only'be'explained the most important individual components of the inventive control valve unit or block. The remaining components will be described in greater detail during the functional description of the invention. I

In the exemplary embodiment of the invention represented in FIG. 1, it will be seen and understood that the inventive control valve block or unit is formed of two components, namely an upper component and a lower component, which can be separated from one another. The lower component constitutes the main control component, directly controls the through-flowing oil, and is designed for a predetermined quantity of oil. When working with greater or smaller quantities of oil, depending upon the elevator to be actuated, this main control component is then dimensioned appropriately different.

The upper component constitutes the precontrol valve. It is operated with a small, practically constant quantity of oil, thus actuates the main control component and can therefore be used for different structural sizes of such main control component, and with which it can be freely exchanged. The precontrol valve under consideration supports the electromagnets 9 and 10 which, during travel of the elevator or lift, actuate switches arranged in the elevator shaft and, therefore, triggers the control functions of the entire control valve block or unit.

CONSTRUCTION OF THE MAIN CONTROL COMPONENT:

The elements designated by reference numerals and 6 constitute the piston and the compression spring of a pressure differential balance of the type, for instance, shown and described in Swiss Pat. No. 444,601. Since pressure differential balances of the aforementioned type are known to the art, the following description will be directed to certain specific aspects thereof necessary for acquiring a complete understanding of the structure and operation of the instant invention. Hence, in order to more fully comprehend this invention, it is here mentioned that the control piston 5 is subjected at one side or face (in this instance the bottom or lower face) to the pressure prevailing in the intermediate channel 3, this pressure being transmitted via the bore 4 to this lower face of the aforementioned piston 5. Furthermore, the other upper face of the piston 5 is subjected to the action of the pressure or compression spring 6 (when the installation is out of operation, that is to say when only the oil pump is in operation, yet magnets 9 and 10 are still not energized) as well as additionally (after energization of the magnets) to the action of the load pressure of the elevator. The balancing of these forces brings about a displacement of the control piston 5 in the upward direction, so that oil, with a load-dependent pressure gradient, can flow from the intermediate channel 3 past the control edge 7 into the return flow channel 8. The main function of this pressure differential balance therefore resides in maintaining a pressure inthe intermediate channel 3 which, when the elevator is moving upwards, is at a constant value above the load pressure in the cylinder of the elevator drive unit, and during downward travel of the elevator is at a constant value below the load pressure in such cylinder of such elevator drive unit. The exact manner in which this function of such pressure difierential balance is achieved will be more fully explained hereinafter under the section dealing with the operation of the invention. Yet, it is of significance to here remark that for both directions of travel of the elevator a single pressure differential balance is sufficient.

Continuing, it should be understood that reference numeral 20 designates a dosing piston member which is subjected to the action or a compression or pressure spring 21. The function of this dosing piston member 20 is to provide operable communication between the consumer (elevator cylinder) and the intermediate channel 3, and further to regulate, that is to 'say, to maintain at an adjustable value, the throughflowing quantity of oil, and finally, to hennetically seal the consumer conduit when the elevator or lift is stationary so that such does not slowly drop. In respectof this latter function the piston member 20 is advantageously constructedas a cone seat valve which bears against an appropriately configured valve seat 56.

The dosing piston member 20 is actuated by a piston 16 which is controlled via a conduit 14 by. the magnet 10, whereas its opposite side is coupled via a conduit 17 directly with the return flow channel 8. So that this actuation need not occur against the full load pressure,

there is advantageously provided a valve member 19' which initially relieves the face of the dosing piston member 21 situated opposite the piston 16, so that there is only acting upon this dosing piston the force of the spring member 21.

CONSTRUCTION OF THE PRECONTROL VALVE UNIT:

This unit embodies both of the electromagnets 9 and 10 equipped with a respective precontrol slide or spool 22 and 11 operably coupled therewith. The slide member 1 1 is coupled via the conduit 12 with the intermediate channel 3 and via the conduit 14 with the actuation piston member 16. When the magnet 10 is deenergized, this communication is interrupted and instead of such, there is obtained a communication of the conduit 14 with the return flow channel 8 through the agency of conduit 51.

The slide member 22 is connected, on the one hand, via a conduit 25 with the elevator cylinder 102 and, on

the other hand, via the conduits 27 and 30 with a control piston member 33 and, therefore, indirectly (through the agency of an annular channel 31, an annular compartment 36 and a conduit 37) with the compression spring side-face of the control piston 5. When the magnet 9 is energized the control piston 5 is positionally influenced by virtue of the pressure prevailing in the elevator or lift cylinder. When this magnet is deenergized the slide member 22, under the action of a spring, is displaced such that the conduits 27 and 30 are likewise operably coupled with the return flow channel 8, and specifically, through the agency of a channel 55.

Furthermore, constituting part of the precontrol valve unit is a reversing piston 39, by means of which it is possible to utilize a single pressure differential balance 5, 6 for both directions of travel of the elevator. This reversing piston is subjected to the action of a spring member 41 at one face thereof. At the other face there opens a conduit 40 leading from the pump connection 1. If the pump 100 is in operation, then, the pump pressure acts upon this face and displaces the piston member 39 against the action of the spring 41. This influences the pre-biasing of a spring 34 and therefore indirectly the position of the previously mentioned control piston 33 bearing at one face against this spring member 34. The piston member 33 is coupled with different channels 30, 32, 37 and 45 and possesses the previously mentioned annular compartment 36 by means of which, depending upon the position of the piston, individual channels can be operatively communicated with one another in flow relationship. Thus, in the event that the channels 30 and 37 are coupled with one another there is provided a pressure gradient or drop which in magnitude is dependent upon the position of the annular compartment 36. Once again, as will be explained hereinafter, from this magnitude there is dependent whether the elevator is moving upwards or downwards.

OPERATION DURING UPWARD TRAVEL The pressurized oil delivered by a displacement pump 100 arrives via the pump connection 1 directly at the main control component and via the nonreturn or check valve 2 at the intermediate channel 3. The buildup of pressure which exists here causes, via the bore 4, raising of the control piston 5 upwardsagainst the force of the compression spring 6. Thus, with a circulation pressure of approximately 4 kp/cm2 there flows the entire pumped quantity of oil via the control edge 7 and the return flow channel 8 back into the oil reservoir 101. This renders possible an almost unloaded high revolution of the pump motor with a star-delta starter. The lifting movement of the cylinder of the elevator drive unit is now initiated by simultaneously switching in the electromagnets 9 and 10. The armature of the magnet 10 pushes the precontrol slide 11 downwards and thus connects the intermediate channel 3 through the agency of the control conduit 12 and the sinter filter 13 with the control channel 14. From this location the pressurized oil arrives via an adjustable throttle 15 beneath the actuation piston member 16. Since the upper surface or face of this piston communicates via the conduit 17 with the return, it is displaced upwards, so that initially the ball check valve 19 is opened via the plunger 18. Consequently, the upper face of the dosing piston member 20, loaded by the spring member 21 and the pressure in the elevator cylinder, communicates with the return. Since now both equal size faces of the dosing piston member are relieved of pressure, a pressure of approximately 2 kp/cm2 beneath the piston member 16 is sufficient in order to raise the dosing piston member 20 against the force of the spring 21. However, this only then occurs when there prevails in the intermediate channel 3 a somewhat higher pressure than in the cylinder of the elevator drive unit, in order to prevent a lowering of the elevator or lift. By virtue of thesimultaneous switching in of the electromagnet 9 together with the electromagnet 10 there immediately increases the pressure in the intermediate channel 3 by a constant value above the pressure in the cylinder, as such will be more fully described hereinafter. The armature of the magnet 9 pushes the precontrol slide 22 upwards. By means of the conical member 23 the cone check valve 24 is opened, so that the oil which is under pressure can flow out of the cylinder 102 via the control conduit 25 and the sinter filter 26 into the control conduit 27. From this location the pressurized oil moves through the conduit 28 both to the lower face of the piston 29 as well as via the conduit 30 into the annular or ring-shaped channel 31 which is in flow communication via the conduit 32 with the lower surface or face of the control piston 33.

Since the upper surface or face of this piston is initially only loaded by the spring member 34, this piston member is displaced upwards and allows pressurized oil to flow via the control edge 35 into the annular com- 6, causes the piston member 5 to assume an intermediate position in which it throttles the oil flow at the control edge 7 to such an extent that the pressure in the intermediate channel 3 is greater by a certain difference than the momentary pressure in the cylinder. This constant pressure differential at the dosing piston 20 now causes a flow ina direction to the cylinder which is only dependent upon the position of the dosing piston 20 and no longer upon the pressure in the cylinder. The pressure differential at the dosing piston member 20 is adjustable between, for instance, 0-4 kp/cm2 by means of the impact or stop screw member 38, so that with the same open cross section there can be controlled different throughflow quantities. The impact screw member 38 limits the stroke of the reversing piston 39 which is upwardly displaced against the force of the spring member 41'by the pump pressure in the connection 1 via the control conduit 40, since the spring compartment is coupled via the conduit 42 with the return.

The position of the reversing piston 39, however, influences the force of the spring member 34 acting upon the control piston 33, which in turn results in enabling a change in the pressure gradient or drop between the annular channel 31 and the annular compartment 36. Since the pressure in the annular compartment 36 acts via the bore 43 upon the upper face of the control piston 33, whereas the pressure in the annular channel 31 acts upon the lower face of control piston 33 through the agency of the bore 32, the piston member 33 is adjusted in its equilibrium position when the pressure in the annular compartment 36 is smaller by the force of the spring 34 than the load pressure in the annular channel 31. The reduced load pressure acts via the control conduit 37, together with the force of the spring member 6, upon the upper face of the control piston 5. Since a pressure of 4 kp/cm2 above the load pressure is required to overcome the spring force, there is sufficient for this purpose a pressure of already 3 kp/cm2 if, for instance, the load pressure is reduced in the pressure gradient valve by 1 kp/cm2.

The opening velocity of the control piston 5 can be influenced by means of the impact or stop screw 44,

. operates very accurately with a difference of maximum 2 kp/cm2 between the openingand closing pressure.

' As will be readily apparent from the preceding description, there thus prevails at the dosing piston member 20 a constant pressure differential during the upward travel of the elevator or lift, so that the entire course of movement of the elevator is dependent upon the displacement or positioning of the dosing piston. The throttle influences the opening velocity of the dosing piston, whereby the acceleration of the elevator can be adjusted. In order to maintain the acceleration constant independent of the load pressure the load pressure is reduced to a constant value by means of the precontrol slide 11 in front of the throttle 15. This is achieved in that the precontrolled pressure in the channel' 14 acts via the bore .47 upon the lower face or surface of the precontrol piston 11 against the force of the electromagnet 10. If this pressure exceeds the force of the magnet, then the flow from the channel 12 to the control edge 48 is throttled, in that the precontrol piston 11 is upwardly displaced. With maximum velocity of the elevator or lift the dosing piston member is pressed against the impact screw 49 by means of which there can be adjusted the largest opening-cross section. Shortly before reaching the selectedstop location the magnet is deenergized by the braking switch which is arranged, in known fashion, in the elevator shaft.

The spring member 50 displaces the precontrol slide 11 upwards into the illustrated position, whereby the control conduit '14 is coupled with the return flow conduit 51. As a result, the spring 21 presses the dosing piston member 20 together with the actuation piston member 16 downwards, so that control oil is displaced via the check valve'52 and the throttle 53 into the return. Since the dosing piston 20 is completely pressure equalized there is provided a continuous deceleration of the elevator independently of the load pressure, which can be adjusted by means of the throttle 53. However, the elevator is decelerated only until the actuation piston 16 impacts against the piston member 29 which is pressed by means of the load pressure in the control conduit 28 against the collar of the impact screw 54. By means of this impact screw 54, it is thus possible to regulate the crawling speed by means of which the elevator can now continue to travel until it is exactly positioned. When it has reached this exact position, then, the magnet 9 is deenergized by means of a conventional holding switch arranged in the elevator shaft, whereby the precontrol piston member 22 is displaced downwardly by spring force to assume the illustrated position. The piston member 29 is now likewise downwardly displaced through the force of the spring member 21, so that control oil is displaced without throttling via the conduits 28 and 27 into the return flow 55. The dosing piston 20 is thus seated very quickly upon the seat 56 and completely closes the throughpassage. At the same time the conduit 30 is also relieved, so that the piston member 5 immediately opens the connection between the pump and the return. The pump can therefore run out unloaded which does not have any influence upon the stopping accuracy of the elevator. Due to the leakage in the annular gap 57, the load pressure at the upper face of the dosing piston 20 builds up and tightly presses such as well as the ball 19 against its seat. Since the check valve 24 is also again closed, no leakage oil whatsoever can escape any longer out of the cylinder compartment. The check valve 58 is only installed for security reasons, in order that the dosing piston 20 does not remain open, or opens if for some reason the magnet 9 is deenergized which would result in the elevator no longer provides any resistance.

OPERATION DURING DOWNWARD TRAVEL:

The operation during downward travel of the elevator or lift is essentially the same as during upward travel thereof and differs only in the following manner: Since the pump during downward travel is not operational, the conduit 40 is without pressure. Consequently, the reversing piston 39 is pressed by means of the spring 41 against the impact screw 59, resulting in ,a larger prebiasing of the spring 34. The pressure drop between the control conduit means 30 and 37 can thus be regulated by the impact screw 59 from 4- kp/cm2 up to, for instance, 8 kp/cm2. Now, if for example a load pressure reduced by 7 kp/cm2 acts upon the upper face of the control piston 5, then a pressure in the intermediate channel 3 which is higher by 4 kp/cm2 is sufficient in order to open the control piston 5 against the spring 6. However, this means that the pressure in the intermediate channel 3 is still below the load pressure by 3 kp/cm2, so that at the dosing piston 20 there now prevails a flow from the elevator cylinder via the intermediate channel 3 to the return.

The downward travel of the lift occurs, therefore, likewise load-independent and braked by means of the control piston 5, whereas the velocity is controlled by the'dosing piston 20. By increasing the pressure drop during the downward travel, in contrast with the upward travel, by means of the impact screw 59 it is possible to regulate the lowering speed so as to be greater than the raising speed of the lift. In so doing, there is also increased the crawling speed in the same relationship.

As already mentioned, during deceleration the magnet 10 is deenergized, so that the control conduit 14 is coupled with the return flow conduit 51 which opens into the return flow channel 8. The return flow therefore flows past the throttles l5 and 53 and is consequently dependent upon their positions, that is to say, from the throttle cross-section, and furthermore, however, also upon the viscosity of the return flowing liquid. Changes in the viscosity therefore also result in changes in the deceleration. This can be prevented in that both of the throttles are opened as wide as possible and the magnet 10 is permitted to remain energized during deceleration, so that the control current of the magnet can be regulated by suitable means, for instance a potentiometer, mechanically actuated by control cams in the elevator shaft or optically by suitable light barrier means. By providing these measures it is possible to eliminate the crawling operation, that is to say, travelling at low speeds prior to reaching the holding location (see FIG. 2). In so doing, it should only be observed that the spring 21 must be replaced by a considerably stronger spring, since now also during acceleration, owing to the elimination of the throttling action of the throttle 15, the piston member 16 is impinged with a considerably higher pressure.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Accordingly what is claimed is:

1. A control valve block assembly for hydraulically operated elevators or the like for the load-independent raising and lowering thereof and employing electromagnetic triggering of the control operation, comprising an elevator drive cylinder unit, a hydraulic pump for a fluid medium and a return flow tank provided for said control valve block assembly, a single pressure differential balance means for both directions of travel of the elevator, said pressure differential balance means incorporating a control piston, means defining an intermediate channel communicating with said cylinder of the elevator drive cylinderunit, said control piston being located in flow communication with said intermediate channel and maintaining the pressure in said intermediate channel at a level deviating from the load pressure in the elevator cylinder by a constant amount, reversing piston means cooperating with said pressure differential balance means for determining the deviation ofsaid pressure to the high side or the low side depending upon the direction of travel of said elevator,. dosing piston means constructed as a sealing seat valve unit which in its open position provides a flow communication from said pressure differential balance means to said cylinder and thus regulates the quantity of hydraulic fluid medium flowing to and from such cylinder, two precontrol slide valve means, two electromagnets each of which is operatively coupled with one of said precontrol slide valve means and when energized actuates its associated precontrol slide valve means, fluid conduit means provided for said precontrol slide valve means and said dosing piston means, one such precontrol slide valve means directly controlling the position of said control piston and the other precontrol slide valve means directly controlling the position of said dosing piston means, spring means acting upon said reversing piston means and an adjustable impact screw cooperating with said reversing piston means, a conduit communicating said pump with said reversing piston means, said reversing piston means during operation of said pump being displaced in one direction against the action of said spring means by virtue of the pressure prevailing in said conduit, and when said pump is inoperable and said conduit is without pressure said reversing piston means being displaced under the action of said spring means in the other direction against said adjustable impact screw.

2. A control valve block assembly as defined in claim 1, further including an adjustable stop screw for limiting the displacement of said reversing piston means in a direction towards said spring means.

3. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, further including a control piston member cooperating with said reversing piston means, springmeans operatively associated with said reversing piston means and said control piston member, said reversing piston acting upon said control piston member via said last-mentioned spring means, a spring member cooperating with said control piston of said pressure differential balance means, and means defining a flow channel for communicating said control piston member with the face of said control piston of said pressure difierential balance means which confronts said spring member.

4. A control valve block assembly for hydraulically operated elevators as defined in claim 3, wherein said control piston member is equipped with a recessed portion defining an annular compartment.

5. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, further including a spring against which bears said dosing piston means, said dosing piston means being provided with a longitudinally extending bore, and a ball valve means arranged in said longitudinally extending bore.

6. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, said dosing piston means being provided with a conical portion, means defining a seat for said conical portion, said conical portion nesting against said seat for the purpose of interrupting the flow communication between said cylinder of the drive unit of the elevator and said intermediate channel.

7. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, further including channel means for communicating said dosing piston means with said intermediate channel, an actuation piston for displacing said dosing piston means, and wherein when one of said electromagnets is energized said dosing piston means communicates via said channel means with said intermediate channel. I

8. A control valve block assembly for hydraulically operated elevators or the like as defined in claim7, wherein said dosing piston means is provided with ball valve means, said actuation piston being equipped with pin means which serves to open said ball valve means prior to beginning the displacement of said dosing piston means.

9. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 7, further including means defining a compartment between said actuation piston and said dosing piston, means providing a return flow channel leading to said return flow tank, and conduit means directly communicating said compartment with said return flow channel.

10. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1,

further including a conduit leading from said cylinder of said drive unit to the precontrol slide valve means of one of said electromagnets, a ball check valve for closing said conduit when said last-mentioned electromagnet is deenergized, a valve seat for said ball check valve unit, said last-mentioned precontrol slide valve means being provided with a conical portion which upon displacement of said precontrol slide valve means raises said ball check valve unit from said valve seat and opens said conduit. I

11. A-control valve block assembly for hydraulically operated elevators or the like as defined in claim 10, further including a control piston member acted upon by said reversing piston means, a further conduit operably associated with said last-mentioned conduit, and a still further conduit communicating said further conduit with said control piston member, wherein when said oneelectromagnet is energized said conduit communicates via a recessed portion provided at said precontrol slide valve means with said further conduit.

12. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 11, wherein said still further conduit leading to said control piston member defines two branch conduits, spring means cooperating with one face of said control piston member, one of said branch conduits leading to the opposite face of said control piston member, means defining an annular channel surrounding said control piston member, the other branch conduit terminating at said annular channel.

13. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 7, wherein said precontrol slide valve means of said electromagnet which is energized regulates the pressure in said channel means leading to said actuation piston at a constant value as a function of the force of said lastmentioned electromagnet acting upon said precontrol slide means. I

l 14. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 13,

member, a further piston with which said additional conduit communicates, stop screw means for limiting further including control edge-means provided for said I control piston member, an annular compartment communicating via said control edge means said still further conduit with said further conduit leading to said control piston of said pressure differential balance means, the throughflow cross-section at the location of this control edge means and therefore the prevailing pressure drop being dependent upon the position of said control piston member determined by the pressure in said one branch line and the pre-bias of said spring acting upon said control piston member.

17. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 4, including a channel leading to said pressure differential balance means, a conduit, a return flow conduit com-' municating with said return flow tank, and wher in when said electromagnets are deenergized said annu ar compartment provides a flow communication from said channel via said conduit to said return flow conduit, and adjustable impact screw means for determining the maximum throughflow cross-section of this flow communication.

18. A control valve block assembly for hydraulically operated elevators or the like as defmedin claim 13, further including a return flow channel communicating with said return flow tank, a further channel communicating with said precontrol slide means of said one electromagnet, wherein when said last-mentioned electromagnet of said precontrol slide means is deenergized said channel leading to said actuation piston is connected with said further channel leading to said return flow channel, and throttle means arranged 'at said further channel. 

1. A control valve block assembly for hydraulically operated elevators or the like for the load-independent raising and lowering thereof and employing electromagnetic triggering of the control operation, comprising an elevator drive cylinder unit, a hydraulic pump for a fluid medium and a return flow tank provided for said control valve block assembly, a single pressure differential balance means for both directions of travel of the elevator, said pressure differential balance means incorporating a control piston, means defining an intermediate channel communicating with said cylinder of the elevator drive cylinder unit, said control piston being located in flow communication with said intermediate channel and maintaining the pressure in said intermediate channel at a level deviating from the load pressure in the elevator cylinder by a constant amount, reversing piston means cooperating with said pressure differential balance means for determining the deviation of said pressure to the high side or the low side depending upon the direction of travel of said elevator, dosing piston means constructed as a sealing seat valve unit which in its open position provides a flow communication from said pressure differential balance means to said cylinder and thus regulates the quantity of hydraulic fluid medium flowing to and from such cylinder, two precontrol slide valve means, two electromagnets each of which is operatively coupled with one of said precontrol slide valve means and when energized actuates its associated precontrol slide valve means, fluid conduit means provided for said precontrol slide valve means and said dosing piston means, one such precontrol slide valve means directly controlling the position of said control piston and the other precontrol slide valve means directly controlling the position of said dosing piston means, spring means acting upon said reversing piston means and an adjustable impact screw cooperating with said reversing piston means, a conduit communicating said pump with said reversing piston means, said reversing piston means during operation of said pump being displaced in one direction against the action of said spring means by virtue of the pressure prevailing in said conduit, and when said pump is inoperable and said conduit is without pressure said reversing piston means being displaced under the action of said spring means in the other direction against said adjustable impact screw.
 2. A control valve block assembly as defined in claim 1, further including an adjustable stop screw for limiting the displacement of said reversing piston means in a direction towards said spring means.
 3. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, further including a control piston member cooperating with said reversing piston means, spring means operatively associated with said reversing piston means and said control piston member, said reversing piston acting Upon said control piston member via said last-mentioned spring means, a spring member cooperating with said control piston of said pressure differential balance means, and means defining a flow channel for communicating said control piston member with the face of said control piston of said pressure differential balance means which confronts said spring member.
 4. A control valve block assembly for hydraulically operated elevators as defined in claim 3, wherein said control piston member is equipped with a recessed portion defining an annular compartment.
 5. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, further including a spring against which bears said dosing piston means, said dosing piston means being provided with a longitudinally extending bore, and a ball valve means arranged in said longitudinally extending bore.
 6. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, said dosing piston means being provided with a conical portion, means defining a seat for said conical portion, said conical portion nesting against said seat for the purpose of interrupting the flow communication between said cylinder of the drive unit of the elevator and said intermediate channel.
 7. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, further including channel means for communicating said dosing piston means with said intermediate channel, an actuation piston for displacing said dosing piston means, and wherein when one of said electromagnets is energized said dosing piston means communicates via said channel means with said intermediate channel.
 8. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 7, wherein said dosing piston means is provided with ball valve means, said actuation piston being equipped with pin means which serves to open said ball valve means prior to beginning the displacement of said dosing piston means.
 9. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 7, further including means defining a compartment between said actuation piston and said dosing piston, means providing a return flow channel leading to said return flow tank, and conduit means directly communicating said compartment with said return flow channel.
 10. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 1, further including a conduit leading from said cylinder of said drive unit to the precontrol slide valve means of one of said electromagnets, a ball check valve for closing said conduit when said last-mentioned electromagnet is deenergized, a valve seat for said ball check valve unit, said last-mentioned precontrol slide valve means being provided with a conical portion which upon displacement of said precontrol slide valve means raises said ball check valve unit from said valve seat and opens said conduit.
 11. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 10, further including a control piston member acted upon by said reversing piston means, a further conduit operably associated with said last-mentioned conduit, and a still further conduit communicating said further conduit with said control piston member, wherein when said one electromagnet is energized said conduit communicates via a recessed portion provided at said precontrol slide valve means with said further conduit.
 12. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 11, wherein said still further conduit leading to said control piston member defines two branch conduits, spring means cooperating with one face of said control piston member, one of said branch conduits leading to the opposite face of said control piston member, means defining an annular channel surrounding said control piston member, the otHer branch conduit terminating at said annular channel.
 13. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 7, wherein said precontrol slide valve means of said electromagnet which is energized regulates the pressure in said channel means leading to said actuation piston at a constant value as a function of the force of said last-mentioned electromagnet acting upon said precontrol slide means.
 14. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 13, further including throttle means provided at said channel means for regulating a predetermined throughflow quantity of fluid medium flowing through the throttle location of said throttle means.
 15. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 11, including an additional conduit connecting with said further conduit leading from said precontrol slide means in a direction towards said control piston member, a further piston with which said additional conduit communicates, stop screw means for limiting the stroke of said further piston, an actuation piston cooperating with said dosing piston means, said further piston limiting the return flow movement of said actuation piston.
 16. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 12, further including control edge means provided for said control piston member, an annular compartment communicating via said control edge means said still further conduit with said further conduit leading to said control piston of said pressure differential balance means, the throughflow cross-section at the location of this control edge means and therefore the prevailing pressure drop being dependent upon the position of said control piston member determined by the pressure in said one branch line and the pre-bias of said spring acting upon said control piston member.
 17. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 4, including a channel leading to said pressure differential balance means, a conduit, a return flow conduit communicating with said return flow tank, and wherein when said electromagnets are deenergized said annular compartment provides a flow communication from said channel via said conduit to said return flow conduit, and adjustable impact screw means for determining the maximum throughflow cross-section of this flow communication.
 18. A control valve block assembly for hydraulically operated elevators or the like as defined in claim 13, further including a return flow channel communicating with said return flow tank, a further channel communicating with said precontrol slide means of said one electromagnet, wherein when said last-mentioned electromagnet of said precontrol slide means is deenergized said channel leading to said actuation piston is connected with said further channel leading to said return flow channel, and throttle means arranged at said further channel. 